Refrigerator and control method thereof

ABSTRACT

Disclosed is a refrigerator including: an ice maker. The ice maker includes a tray; a water supplier configured to supply water into the tray; a heater configured to heat water supplied into the tray; a cooler configured to cool the tray; a condensate collector configured to collect water vapor from the tray, separate the collected water vapor into condensate and air, and transfer the separated condensate to the water supplier; and a controller configured to control the water supplier and the heater to generate the water vapor by raising a temperature of water supplied into the tray above a boiling point, and controlling the cooler to turn water, of which a dissolved air concentration is reduced due to the generation of the water vapor, in the tray into ice.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application PCT/KR2021/019166, filed on Dec. 16, 2021, and is based on and claims priority to Korean Patent Application No. 10-2021-0003842 filed on Jan. 12, 2021, the disclosures of which are incorporated by reference herein in their entireties.

BACKGROUND 1. Field

The disclosure relates to a refrigerator for cooling things stored therein to a predetermined temperature and keeping that state and a method of controlling the same, and more particularly to a refrigerator having a structure for making highly transparent ice in a tray of a freezer compartment by water supplying and cooling processes and a method of controlling the same.

2. Description of Related Art

A refrigerator is one of various household appliances, and refers to an apparatus that accommodates predetermined things in an accommodating space of an insulated housing and keeps the things cooled and frozen using a refrigerant. The refrigerator includes a freezer compartment partitioned from a refrigerator compartment and adjustable to a sub-zero temperature, and makes ice by supplying water to a box-shaped tray in the freezer compartment and freezing the tray. The ice made in this way typically has low transparency and a cloudy appearance, and is prone to crack when subjected to sudden temperature changes. However, a refrigerator capable of making highly transparent ice may be required for a variety of reasons such as an aesthetic point of view felt by a user when using ice or a demand for hard ice.

The transparency of ice depends on the concentration of air dissolved in water when the water is being frozen. The more the amount of air dissolved in water before freezing, the lower the transparency of ice after the freezing. In other words, to make ice with high transparency, the concentration of air dissolved in water prior to the freezing is required to be as low as possible.

Various methods have been proposed to make highly transparent ice. However, conventional methods have many problems such as a relatively long time required to make the highly transparent ice, uneven transparency between pieces of ice, and relatively low transparency. Accordingly, a refrigerator is required to make highly transparent ice in a relatively short time.

SUMMARY

According to an embodiment of the disclosure, there is provided a refrigerator including: an ice maker including: a tray; a water supplier to supply water into the tray; a heater configured to heat water supplied into the tray; a cooler configured to cool the tray; a condensate collector configured to collect water vapor from the tray, separate the collected water vapor into condensate and air, and transfer the separated condensate to the water supplier; and a controller configured to control the water supplier and the heater to generate the water vapor by raising a temperature of water supplied into the tray above a boiling point, and controlling the cooler to turn water, of which a dissolved air concentration is reduced due to the generation of the water vapor, in the tray into ice.

Further, the refrigerator may further include a pump configured to perform a pumping operation to adjust an internal pressure of the tray upon water being supplied to the tray, wherein the controller is configured to control the water supplier to supply water into the tray while controlling the pump to lower the internal pressure of the tray below an external pressure of the refrigerator.

Further, the condensate collector may be configured to transfer air separated from the collected water vapor to the pump.

Further, the controller may be configured to control the cooler to cool the tray, based on an internal pressure of the tray exceeding a threshold after supplying water into the tray.

Further, the refrigerator may further include: a condensate confluent pipe connecting the condensate collector and the water supplier, and a condensate confluent pipe valve configured to open and close the condensate confluent pipe, wherein the controller is configured to control the condensate confluent pipe valve to close the condensate confluent pipe upon water being supplied to the tray through the water supplier, and to open the condensate confluent pipe upon condensate being supplied from the condensate collector to the water supplier.

Further, the refrigerator may further include: a condensate confluent pipe connecting the condensate collector and the water supplier, and a confluent valve configured to selectively open and close the condensate confluent pipe and the water supplier, wherein the controller is configured to control the confluent valve to close the condensate confluent pipe and open the water supplier upon water being supplied to the tray through the water supplier, and to open the condensate confluent pipe and close the water supplier upon condensate being supplied from the condensate collector to the water supplier.

Further, the heater may extend along the water supplier so as to be adjacent to the water supplier.

Further, the heater may be adjacent to the tray so as to be positioned to heat the tray.

Further, the water supplier may include a water supply valve controlled by the controller to open and close the water supplier.

Further, the cooler may include a refrigerant pipe adjacent to the tray.

Further, the refrigerant pipe may be adjacent to the condensate collector to cool water vapor collected in the condensate collector.

Further, according to an embodiment of the disclosure, there is provided a method of controlling a refrigerator, including: heating water by a heater and supplying the heated water to a tray of an ice maker by a water supplier so as to generate water vapor by raising a temperature of water supplied into the tray above a boiling point; cooling the tray by a cooler so as to turn water, of which a dissolved air concentration is reduced due to the generation of the water vapor, in the tray into ice; and collecting water vapor from the tray by a condensate collector, separating the collected water vapor into condensate and air, and transferring the separated condensate to the water supplier.

Further, the supplying the heated water to the tray may include lowering an internal pressure of the tray below an external pressure of the refrigerator.

The transferring the separated condensate to the water supplier may include transferring air separated from the collected water vapor to a pump configured to adjust an internal pressure of the tray.

The cooling the tray may include cooling the tray, based on an internal pressure of the tray exceeding a threshold after supplying water into the tray.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a refrigerator.

FIG. 2 is a lateral cross-sectional view of the refrigerator of FIG. 1 .

FIG. 3 is a front perspective view of an ice maker viewed from above.

FIG. 4 is a rear perspective view of an ice maker viewed from above.

FIG. 5 is a perspective view of an ice maker viewed from below.

FIG. 6 is a cross-sectional view schematically showing the internal structure of a tray.

FIG. 7 is a block diagram of an ice maker.

FIG. 8 schematically illustrates a principle of making ice in an ice maker.

FIG. 9 is a flowchart showing how an ice maker controls ice.

FIG. 10 is a graph showing a phase diagram of water in terms of temperature and pressure.

FIG. 11 is a perspective view of a tray and a condensate collector according to another embodiment.

FIG. 12 is a lateral cross-sectional view of the tray and the condensate collector of FIG. 11 .

FIG. 13 illustrates a principle of a valve that selectively opens and closes a water pipe and a condensate confluent pipe.

DETAILED DESCRIPTION

Below, embodiments will be described in detail with reference to accompanying drawings. Further, the embodiments described with reference to the accompanying drawings are not exclusive to each other unless otherwise mentioned, and a plurality of embodiments may be selectively combined within one apparatus. The combination of these plural embodiments may be discretionally selected and applied to realize the present inventive concept by a person having an ordinary skill in the art.

In the description of the embodiments, an ordinal number used in terms such as a first element, a second element, etc. is employed for describing variety of elements, and the terms are used for distinguishing between one element and another element. Therefore, the meanings of the elements are not limited by the terms, and the terms are also used just for explaining the corresponding embodiment without limiting the disclosure.

Further, a term “at least one” among a plurality of elements in the disclosure represents not only all the elements but also each one of the elements, which excludes the other elements or all combinations of the elements.

FIG. 1 is a perspective view of a refrigerator.

FIG. 2 is a lateral cross-sectional view of the refrigerator of FIG. 1 .

As shown in FIGS. 1 and 2 , a refrigerator 1 includes a housing 10 forming an outer appearance. The housing 10 is internally provided with a storage compartment 20 opened frontwards and accommodating predetermined things to be refrigerated. A door 30 is rotatably coupled to the housing 10 to open and close a front opening side of the storage compartment 20. A hinge 40 is coupled between the housing 10 and the door 30 to enable the door to rotate with respect to the housing 10.

In the accompanying drawings, directions will be defined. An X direction refers to left and right directions of the refrigerator 1. A Y direction is orthogonal to the X direction and refers to a frontward direction of the refrigerator 1. In other words, when the door 30 is opened, the storage compartment 20 is opened toward the Y direction. A Z direction is orthogonal to both the X direction and the Y direction, and refers to the longitudinal direction of the refrigerator 1.

The refrigerator 1 in this embodiment has a structure where four doors 30 are opened and closed leftwards and rightwards and the storage compartment 20 is partitioned into three compartments, but the structure of the refrigerator 1 is not limited to this embodiment. For example, the refrigerator 1 may include only one door 30 or may include two doors 30. The storage compartment 20 may not be partitioned into a plurality of compartments, or may be partitioned into two compartments. The hinge 40 may be provided on the left side of the front of the housing 10 so that the door 30 can pivot about the left edge of the front of the housing 10, and may be provided on the right side of the front of the housing 10 so that the door 30 can pivot about the right edge of the front of the housing 10.

The housing 10 includes an inner casing 11 forming the storage compartment 20, and an outer casing 13 accommodating the inner casing 11 and forming the outer appearance. The inner casing 11 and the outer casing 13 are spaced apart from each other, and a space between the inner casing 11 and the outer casing 13 is filled with an insulator 15 as a foam to prevent cold air from leaking from the storage compartment 20. There are no limits to the material of the insulator 15, and the material of the insulator 15 may for example include urethane.

The housing 10 includes a partition wall 17 for partitioning the storage compartment 20 into left and right compartments or upper and lower compartments. The storage compartment 20 may be partitioned into a refrigerator compartment 21 and a freezer compartment 23 by the partition wall 17. The refrigerator compartment 21 and the freezer compartment 23 are just named based on their functions, and the storage regions of the storage compartment 20 partitioned by the partition wall 17 may be switched between the refrigerator compartment 21 and the freezer compartment 23 according to temperature settings. The storage compartment 20 is internally provided with a plurality of shelves 25 and a plurality of storage containers 27 to put things to be refrigerated thereon and therein.

The door 30 is coupled to the housing 10 by the hinge 40 and covers the open front of the storage compartment 20. The door 30 opens and closes the storage compartment 20 by pivoting with respect to the housing 10. The side of the door which comes into contact with the housing 10 when the door closes the housing 10, a member made of a rubber or the like material may be provided to maintain the airtightness of the storage compartment 20.

When the storage compartment 20 is partitioned into the refrigerator compartment 21 and the freezer compartment 23 by the partition wall 17, the door 30 includes a refrigerator compartment door 31 for opening and closing the refrigerator compartment 21, and a freezer compartment door 33 for opening and closing the freezer compartment 23. The accommodating space of the housing 10 is divided into a plurality of storage compartments 20, and the plurality of doors 30 are provided to independently open and close the storage compartments 20, thereby minimizing the loss of cold air in the housing 10 as much as possible. Further, a plurality of door guards 35 is provided on the rear side of the refrigerator compartment door 31 or the freezer compartment door 33 to accommodate relatively small things to be refrigerated therein.

The refrigerator 1 has a cooling mechanism that supplies cold air to the storage compartment 20 based on the principle of exchanging heat with a refrigerant. The cooling mechanism includes a compressor 51 for compressing the refrigerant, a condenser for condensing the refrigerant to cause an exothermic reaction, an evaporator 53 for evaporating the refrigerant to cause an endothermic reaction, a blowing fan 55 for blowing air, and a cold air duct 57 for guiding the movement of air cooled by the evaporator 53. Thus, the refrigerator 1 forms a cooling cycle to discharge the cold air to the storage compartment 20, thereby lowering the temperature of the storage compartment 20.

The compressor 51 and the condenser are disposed in a component compartment 29 located in a rear lower side of the housing 10. The component compartment 29 accommodates various components therein to operate the refrigerator 1. The evaporator 53, the blowing fan 55, and the cold air duct 57 are typically disposed behind the storage compartment 20 without interfering with the loading or unloading of things to be refrigerated into or out of the storage compartment 20. However, the locations of the components of the cooling mechanism are not limited to this embodiment.

According to an embodiment of the disclosure, the refrigerator 1 includes an ice maker 1000 to make ice in the freezer compartment 23. The ice maker 1000 in this embodiment is located at one side inside the freezer compartment 23, but the location of the ice maker 1000 is not limited to this embodiment. For example, the ice maker 1000 may be located behind the freezer compartment door 33. The ice maker 1000 receives water from a predetermined water supply tank and freezes the water, thereby making highly transparent ice.

Below, the ice maker 1000 according to an embodiment will be described.

FIG. 3 is a front perspective view of an ice maker viewed from above.

FIG. 4 is a rear perspective view of an ice maker viewed from above.

FIG. 5 is a perspective view of an ice maker viewed from below.

FIG. 6 is a cross-sectional view schematically showing the internal structure of a tray.

As shown in FIGS. 3, 4, 5 and 6 , the ice maker 1000 according to an embodiment includes a tray 1100. The tray 1100 has an accommodating space to store water or ice therein. The tray 1100 includes an outer tray 1110 having a rectangular parallelepiped shape with an opening formed thereon. The outer tray 1110 includes a metal material excellent in thermal conductivity, thereby transferring cold air or heat from the outside to an inner accommodating space. The tray 1100 includes an upper cover 1120 pivotally coupled to an upper surface of the outer tray 1110 by a hinge 1130. The upper cover 1120 pivots about the hinge 1130, thereby opening or closing the accommodating space in the tray 1100. In addition, there may be a structure for sealing the inside of the tray 1100 in an area where the upper cover 1120 and the tray 1100 come into contact with each other when the upper cover 1120 closes the opening of the tray 1100 (in more detail, the outer tray 1110). There may be various examples of such a sealing structure. As one example, a rubber member for preventing external air from entering and exiting the accommodating space of the tray 1100 may be provided in the foregoing area of the upper cover 1120.

Further, the upper cover 1120 may include a component compartment pressure sensor connecting portion 1121 formed from the outside of the tray 1100 to communicate with the accommodating space of the tray 1100. A pressure sensor for measuring the pressure in the accommodating space of the tray 1100 may be connected to the pressure sensor connecting portion 1121. However, there are no limits to a structure where such a pressure sensor is placed and a method by which the pressure sensor measures the pressure in the accommodating space of the tray 1100. Alternatively, the upper cover 1120 may be designed not to include the pressure sensor connecting portion 1121, and the pressure sensor may be placed inside the tray 1100.

The tray 1100 includes a water supplier connecting portion 1140 (see FIG. 6 ) formed at one side of the tray 1100. The water supplier connecting portion 1140 is provided to supply water from the outside to the accommodating space of the tray 1100. In this embodiment, the water supplier connecting portion 1140 includes a hole that communicates with the accommodating space of the tray 1100.

The tray 1100 includes a condensate collector connecting portion 1150 formed at one side of the tray 1100. The condensate collector connecting portion 1150 is provided to discharge water vapor from the accommodating space of the tray 1100 to the outside of the tray 1100. In this embodiment, the condensate collector connecting portion 1150 includes a hole that communicates with the accommodating space of the tray 1100.

The tray 1100 includes an inner tray 1160 accommodated in the outer tray 1110. The inner tray 1160 is filled with water supplied into the tray 1100, and accommodates ice formed by freezing water. The inner tray 1160 is internally provided with an ice guide 1170 to divide ice into multiple pieces. The inner tray 1160 is provided to be separable from the outer tray 1110 when the upper cover 1120 is opened. A user easily obtain ice in the inner tray 1160 by separating the inner tray 1160 from the accommodating space in the outer tray 1110.

Further, referring back to FIG. 3 , the ice maker 1000 includes a water supplier 1200 provided to supply water to the accommodating space of the tray 1100. The water supplier 1200 includes a water pipe 1210 connected to the water supplier connecting portion 1140 of the tray 1100 and forming a path of water supplied to the accommodating space of the tray 1100. The water pipe 1210 is extended from a predetermined source for storing or supplying water to the tray 1100, and includes a channel formed therein. There are no limits to the materials of the water pipe 1210. However, as one example, the water pipe 1210 includes a metal material having high thermal conductivity so that the temperature of water passing through the channel can be easily increased by heat from the outside.

The water supplier 1200 includes a water supply valve 1220 provided in the water pipe 1210 or the water supplier connecting portion 1140 and adjusting the amount of water supplied through the water pipe 1210. The water supply valve 1220 opens and closes the channel of the water pipe 1210 to turn on or off the water supply to the accommodating space of the tray 1100. Further, the water supply valve 1220 adjust the opening area of the channel of the water pipe 1210, thereby controlling the amount of water supplied per unit time. There are no limits to the structure of the water supply valve 1220. For example, the water supply valve 1220 may be implemented as a solenoid valve.

Further, the ice maker 1000 includes a heater 1300 provided to heat water supplied to the accommodating space of the tray 1100. The heater 1300 may have any structure capable of generating heat, and may for example include a metal material for converting applied voltage into heat. The heater 1300 is shaped like a pipe extended along the water pipe 1210, thereby heating water flowing in the water pipe 1210.

Further, the heater 1300 may be designed to be adjacent to the tray 1100 so as to apply heat from the outside of the tray 1100 to the inside of the tray 1100. In this case, the heater 1300 is disposed adjacent to the water pipe 1210 to heat water supplied to the accommodating space of the tray 1100, and also adjacent to the tray 1100 to easily separate ice from the tray 1100.

Further, the ice maker 1000 includes a cooler 1400 provided to cool the tray 1100. The cooler 1400 may have various structures to cool water accommodated in the tray 1100, more specifically, the accommodating space in the tray 1100. For example, the cooler 1400 includes one or more refrigerant pipes 1410 disposed adjacent to the tray 110 and allowing the refrigerant to flow therein. In this embodiment, the refrigerant pipe 1410 is disposed adjacent to a predetermined first lateral wall of the tray 1100, and disposed adjacent to a second lateral wall of the tray 110 opposite to the first lateral wall. The refrigerant pipe 1410 may be disposed to be spaced apart at a predetermined distance from the tray 1100 or may be disposed to be in contact with the tray 1100 as long as it can transfer cold air based on the refrigerant to the tray 1100. However, the number of refrigerant pipes 1410, the position where the refrigerant pipe 1410 is disposed, the length of the refrigerant pipe 1410, the diameter of the refrigerant pipe 1410, the amount of refrigerant flowing in the refrigerant pipe 1410, etc. may be variously designed without being limited only to those of this embodiment.

Further, the ice maker 1000 includes a pump 1500 that performs a pumping operation to adjust the pressure in the tray 1100. There are no limits to the position of the pump 1500. For example, the pump 1500 may be provided to communicate with a condensate collector 1600 (to be described later). The condensate collector 1600 communicates with the tray 1100, and thus the pump 1500 adjusts the pressure in the tray 1100 through the condensate collector 1600.

Further, the ice maker 1000 includes the condensate collector 1600 provided to communicate with the tray 1100, collecting water vapor from the tray 1100, separating the water vapor into condensate and air, an transmitting the separated condensate to the water supplier 1200. The condensate collector 1600 has a space into which water vapor flows, and separates the water vapor flowing therein into condensate and air. The condensate collector 1600 may employ various structures for lowering the temperature of the water vapor flowing therein. For example, the condensate collector 1600 may include a heat pipe, a heat sink, and the like structure for dissipating heat. There are no limits to the material of the condensate collector 1600. For example, the condensate collector 1600 may include a metal material excellent in thermal conductivity.

Further, the condensate collector 1600 is disposed adjacent to the refrigerant pipe 1410, receives cold air from the refrigerant pipe 1410, and easily separate the condensate from the water vapor. In this embodiment, for example, the refrigerant pipe 1410 is disposed in a space between the tray 1100 and the condensate collector 1600, so that the refrigerant pipe 1410 can cool both the tray 1100 and the condensate collector 1600.

The condensate collector 1600 is connected to the pump 1500 at an upper side thereof. Further, the condensate collector 1600 includes a condensate confluent pipe 1610 connected to a lower side thereof. The condensate confluent pipe 1610 connects the lower side of the condensate collector 1600 and the water pipe 1210. Water vapor flowing into the condensate collector 1600 is separated into condensate and air. The condensate falls to the bottom inside the condensate collector 1600 and is then supplied to the water pipe 1210 via the condensate confluent pipe 1610. Air separated from the water vapor is directed to the pump 1500. In this way, the water vapor is not directly transferred to the pump 1500, and only air is transferred to the pump 1500 after the condensate is separated from the water vapor, thereby preventing the pump 1500 from being damaged by water.

The condensate collector 1600 may include a condensate collector connecting portion valve 1620 for opening and closing a condensate collector connecting portion 1150 (see FIG. 6 ). The condensate collector connecting portion valve 1620 allows the water vapor in the tray 1100 to flow into the condensate collector 1600 when opened, and blocks communication between the tray 1100 and the condensate collector 1600 when closed. However, when the airtightness of the tray 1100 is ensured without the condensate collector connecting portion valve 1620 (for example, when only a condensate confluent pipe valve 1630 (to be described later) is sufficient to maintain the internal pressure of the tray 1100), it may be designed not to include the condensate collector connecting portion valve 1620.

The condensate collector 1600 includes the condensate confluent pipe valve 1630 to open and close the condensate confluent pipe 1610. The condensate confluent pipe valve 1630 allows the condensate in the condensate collector 1600 to be transferred to the water pipe 1210 when opened, and prevents water in the water pipe 1210 from flowing back to the condensate collector 1600 when closed.

Below, the structure for controlling the operations of the ice maker 1000 will be described.

FIG. 7 is a block diagram of an ice maker.

As shown in FIGS. 3 to 7 , the ice maker 1000 performs control for operations of various elements through a controller 1800.

The ice maker 1000 includes a pressure sensor 1710 to measure the pressure of the accommodating space in the tray 1100. The pressure sensor 1710 transmits a measurement result to the controller 1800, so that the controller 1800 can identify the internal pressure of the tray 1100 in real time.

The ice maker 1000 includes a temperature sensor 1720 to measure the temperature of water supplied to the tray 1100. The temperature sensor 1720 may be installed in one of the inside of the tray 1100, the water supplier connecting portion 1140, the water pipe 1210, and the heater 1300. The temperature sensor 1720 transmits a measurement result to the controller 1800 in real time, so that the controller 1800 can identify the temperature of water supplied to the tray 1100 in real time.

The controller 1800 includes various types of hardware chipsets such as a central processing unit (CPU), a processor, a microprocessor, a microcontroller, and a system on chip (SoC). The controller 1800 may be an element configured to control the entire refrigerator including the ice maker 1000, or may be a dedicated element provided for the ice maker 1000. The controller 1800 transmits a control signal to an element to be controlled, thereby controlling the operations of that element. According to an embodiment, the controller 1800 may, for example, control the water supply valve 1220, the condensate collector connecting portion valve 1620, and the condensate confluent pipe valve 1630 to be opened and closed. Further, the controller 1800 may control the heat dissipation temperature of the heater 1300. Further, the controller 1800 may control the pumping operations of a water supply pump 1230, a refrigerant pump 1420, and the pump 1500. The water supply pump 1230 performs the pumping operation to transfer water through the water pipe 1210. However, it may be designed that water is supplied without the water supply pump 1230 by pressure difference in the tray 1100 when the water supply valve 1220 is opened. The refrigerant pump 1420 performs the pumping operation to transfer the refrigerant through the refrigerant pipe 1410.

With the foregoing structure of the ice maker 1000, it will be described how to make highly transparent ice.

FIG. 8 schematically illustrates a principle of making ice in an ice maker.

FIG. 9 is a flowchart showing how an ice maker controls ice.

As shown in FIGS. 7, 8 and 9 , the controller 1800 operates as follows to make ice. In an initial state, the inside of the tray 1100 is empty.

At operation 910 the controller 1800 closes the water supply valve 1220, the condensate collector connecting portion valve 1620, and the condensate confluent pipe valve 1630, and drives the pump 1500, thereby lowering the internal pressure of the tray 1100 up to a predetermined level. In other words, the controller 1800 keeps the inside of the tray 1100 sealed, and controls the internal pressure of the tray 1100 to be lower than the external pressure (e.g., 1 atmosphere) through the pumping operation of the pump 1500.

At operation 920 the controller 1800 uses the pressure sensor 1710 to identify whether the internal pressure of the tray 1100 is lowered up to a preset level. When it is detected that the pressure is not lowered up to that level, the controller 1800 controls the pump 1500 to continue to perform the pumping operation.

When it is detected that the internal pressure of the tray 1100 is lowered up to a necessary level, at operation 930 the controller 1800 stops the pump 1500, operates the heater 1300, and opens the water supply valve 1220. By stopping the pump 1500 while the tray 1100 is sealed, the internal pressure of the tray 1100 is maintained at the necessary level. By operating the heater 1300, water flowing in the water pipe 1210 is heated. When the water supply valve 1220 is opened, heated water is supplied to the inside of the tray 1100 through the water pipe 1210 because the internal pressure of the tray 1100 is lower than the external pressure. Meanwhile, the controller 1800 may separately drive the water supply pump 1230 to make water flow in the water pipe 1210.

At operation 940 the controller 1800 closes the water supply valve 1220 and stops the heater 1300 when a preset amount of water has been supplied (for example, when a predetermined period of time during which it is predicted that a preset amount of water has been supplied has been elapsed). When the internal pressure of the tray 1100 is relatively lowered, the boiling point of water is lowered (for example, water boils even at a room temperature below 100 degrees Celsius), and a transition section of water from gas phase to the solid phase becomes relatively short. In this state, when heated water is accommodated in the tray 1100, the temperature of water rises above the boiling point and evaporates while rapidly decreasing the concentration of air dissolved in water. Further, the generation of water vapor causes the internal pressure of the tray 1100 to increase.

At operation 950 the controller 1800 identifies whether the internal pressure of the tray 1100 exceeds a threshold. When the internal pressure of the tray 1100 does not exceed the threshold, the controller 1800 maintains the current state.

Meanwhile, when the internal pressure of the tray 1100 exceeds the threshold, at operation 960 the controller 1800 operates the pump 1500 and the refrigerant pump 1420 and opens the condensate collector connecting portion valve 1620 and the condensate confluent pipe valve 1630. Alternatively, the controller 1800 may be designed to maintain the operation of the heater 1300 so that water in the tray 1100 can reach the boiling point more rapidly at a point in time when the water supply valve 1220 is closed, and stop the heater 1300 at a point in time when the refrigerant pump 1420 operates. By the operation of the pump 1500, the internal pressure of the tray 1100 decreases and water vapor in the tray 1100 moves to the condensate collector 1600 via the condensate collector connecting portion valve 1620. By the operation of the refrigerant pump 1420, water is cooled in the tray 1100 and the water vapor moved to the condensate collector 1600 is separated into condensate and air. The separated condensate moves to the water pip 1210 via the condensate confluent pipe valve 1630. The separated air moves to the pump 1500.

At operation 970 the controller 1800 closes the condensate collector connecting portion valve 1620 when it is identified that all the water vapor in the tray 1100 is collected in the condensate collector 1600 (or when a preset period of time during which it is predicted that all the water vapor in the tray 1100 is collected in the condensate collector 1600 has been elapsed). The controller 1800 drives the refrigerant pump 1420 to keep ice in the tray 1100 from melting. When an event that a user is trying to take out ice is detected, the controller 1800 may additionally perform an operation of driving the heater 1300 to heat the tray 1100 so that ice can be more easily separated from the tray 1100.

According to such operations, the refrigerator 1 may make ice with relatively high transparency. Below, a principle of making highly transparent ice according to an embodiment will be described.

FIG. 10 is a graph showing a phase diagram of water in terms of temperature and pressure.

As shown in FIGS. 8 and 10 , water has one of three phases depending on the temperature and the pressure. For example, under 1 atmosphere, water is solid at temperatures lower than degrees Celsius (i.e., the freezing point B), gaseous at temperatures higher than 100 degrees Celsius (i.e., the boiling point C), and liquid at temperatures between 0 and 100 degrees. However, at atmospheric pressure higher than 1 atmosphere, for example, 217.75 atmospheres, the boiling point (E) is higher than that at 1 atmosphere, and the freezing point (D) is lower than that at 1 atmosphere. On the other hand, at atmospheric pressure lower than 1 atmosphere, the boiling point is lower than that at 1 atmosphere and the freezing point is higher than that at 1 atmosphere. For example, at 0.0060 atmosphere, the boiling point and the freezing point overlap (A). In other words, a difference in temperature required to be lowered for the transition of water from the gas phase to the solid phase increases as the atmospheric pressure increases, and the difference in temperature required to be lowered for the transition of water from the gas phase to the solid phase decreases as the atmospheric pressure decreases. In the case of the point A of atmosphere or below, water directly changes from the gas phase to the solid phase without passing through the liquid phase.

In this embodiment, heated water is supplied to the tray 1100 in the state that the internal pressure of the tray 1100 is lowered. For example, when the tray 1100 has an internal pressure of 0.4 atmosphere, the boiling point of water is about 77 degrees. When the tray 1100 has an internal pressure of 0.04 atmosphere, the boiling point of water is about 25 degrees, room temperature. In other words, when the interior pressure of the tray 1100 is sufficiently low, water boils at a temperature much lower than 100 degrees without raising the temperature of water up to 100 degrees. Because air bubbles are rapidly discharged from boiling water, the concentration of air dissolved in water is relatively rapidly lowered. Further, the longer a section where water goes from the gas phase to the solid phase due to decrease in temperature, the more likely it is that the concentration of air dissolved in water increases again. In this embodiment, the foregoing section is shortened by lowering the pressure, and therefore the concentration of air dissolved in water is maximally suppressed from increasing again while cooling water.

Based on such a principle, the ice maker 1000 according to this embodiment can make highly transparent ice.

In the foregoing embodiments, some elements may be subjected to various design changes. Below, a few examples will be described.

FIG. 11 is a perspective view of a tray and a condensate collector according to another embodiment.

FIG. 12 is a lateral cross-sectional view of the tray and the condensate collector of FIG. 11 .

As shown in FIGS. 11 and 12 , a tray 2100 according to an embodiment is provided to connect with a condensate collector 2200. The condensate collector 2200 is extended in the Y direction in parallel with the X directional lateral wall of the tray 2100, and connected to the inside of the tray 2100 through a condensate collector connecting portion 2300 extended along the Y direction in an upper portion of the tray 2100. The condensate collector connecting portion 2300 forms a hole elongated in the Y direction and allows water vapor in the tray 2100 to move faster than that in the foregoing embodiment. There are no limits to the position of the condensate collector connecting portion 2300. However, the condensate collector connecting portion 2300 may be positioned in the upper portion of the tray 2100 close to an upper cover 2110, considering that water vapor inside the tray 2100 rises toward the upper cover 2110.

The tray 2100, the condensate collector 2200, and the condensate collector connecting portion 2300 may be designed to be molded as a single body. Alternatively, the tray 2100 and the condensate collector connecting portion 2300 may be formed as a single body, and the condensate collector 2200 may be coupled to the condensate collector connecting portion 2300. Alternatively, the condensate collector 2200 and the condensate collector connecting portion 2300 may be formed as a single body, and the tray 2100 may be coupled to the condensate collector connecting portion 2300.

The condensate collector 2200 includes an air outlet 2210 formed to discharge air, and a condensate outlet 2220 formed to discharge condensate. The air outlet 2210 is connected to the pump 1500 (see FIG. 3 ), and the condensate outlet 2220 is connected to the water pipe 1210 (see FIG. 3 ). The condensate outlet 2220 is disposed adjacent to the bottom of the condensate collector 2200 so as to discharge the condensate from the condensate collector 2200. The air outlet 2210 may be provided at any position in the condensate collector 2200 as long as it is positioned above the condensate outlet 2220.

FIG. 13 illustrates a principle of a valve that selectively opens and closes a water pipe and a condensate confluent pipe.

As shown in FIG. 13 , the condensate confluent pipe 1610 is connected to the water pipe 1210, so that the condensate flowing through the condensate confluent pipe 1610 can be supplied to the water pipe 1210. In this regard, the relevant structure has been described in the foregoing embodiment, and therefore detailed descriptions thereof will be omitted. A confluent valve 3000 according to this embodiment is provided in an area where the water pipe 1210 and the condensate confluent pipe 1610 are connected. Unlike the condensate confluent pipe valve 1630 (see FIG. 3 ) of the foregoing embodiment, the confluent valve 3000 is selectively shifted between a first state P1 where the water pipe 1210 is opened and the condensate confluent pipe 1610 is closed, and a second state P2 where the water pipe 1210 is closed and the condensate confluent pipe 1610 is opened. The operations of opening and closing the confluent valve 3000 are performed by the controller 1800 (see FIG. 7 ).

At an initial point in time when water is supplied through the water pipe 1210, the confluent valve 3000 is in the first state P1. Thus, water is prevented from flowing from the water pipe 1210 back to the condensate confluent pipe 1610. Later, at a point in time when condensate is collected through the water pipe 1210, the confluent valve 3000 is in the second state P2. Thus, the condensate is preferentially joined to the water pipe 1210 from the condensate confluent pipe 1610. In this way, the confluent valve 3000 is used to not only prevent water from flowing back to the condensate confluent pipe 1610, but also preferentially recycle the condensate. 

What is claimed is:
 1. A refrigerator comprising: an ice maker including: a tray, a water supplier configured to supply water into the tray, a heater configured to heat water supplied into the tray, a cooler configured to cool the tray, a condensate collector configured to collect water vapor from the tray, separate the collected water vapor into condensate and air, and transfer the separated condensate to the water supplier, and a controller configured to control the water supplier and the heater to generate the water vapor by raising a temperature of water supplied into the tray above a boiling point, and controlling the cooler to turn water, of which a dissolved air concentration is reduced due to the generation of the water vapor, in the tray into ice.
 2. The refrigerator of claim 1, further comprising: a pump configured to perform a pumping operation to adjust an internal pressure of the tray upon water being supplied to the tray, wherein the controller is configured to control the water supplier to supply water into the tray while controlling the pump to lower the internal pressure of the tray below an external pressure of the refrigerator.
 3. The refrigerator of claim 2, wherein the condensate collector is configured to transfer air separated from the collected water vapor to the pump.
 4. The refrigerator of claim 1, wherein the controller is configured to control the cooler to cool the tray, based on an internal pressure of the tray exceeding a threshold after supplying water into the tray.
 5. The refrigerator of claim 1, further comprising: a condensate confluent pipe connecting the condensate collector and the water supplier, and a condensate confluent pipe valve configured to open and close the condensate confluent pipe, wherein the controller is configured to control the condensate confluent pipe valve to close the condensate confluent pipe upon water being supplied to the tray through the water supplier, and to open the condensate confluent pipe upon condensate being supplied from the condensate collector to the water supplier.
 6. The refrigerator of claim 1, further comprising: a condensate confluent pipe connecting the condensate collector and the water supplier, and a confluent valve configured to selectively open and close the condensate confluent pipe and the water supplier, wherein the controller is configured to control the confluent valve to close the condensate confluent pipe and to open the water supplier upon water being supplied to the tray through the water supplier, and to open the condensate confluent pipe and close the water supplier upon condensate being supplied from the condensate collector to the water supplier.
 7. The refrigerator of claim 1, wherein the heater extends along the water supplier so as to be adjacent to the water supplier.
 8. The refrigerator of claim 7, wherein the heater is adjacent to the tray so as to be positioned to heat the tray.
 9. The refrigerator of claim 1, wherein the water supplier includes a water supply valve controlled by the controller to open and close the water supplier.
 10. The refrigerator of claim 1, wherein the cooler includes a refrigerant pipe adjacent to the tray.
 11. The refrigerator of claim 10, wherein the refrigerant pipe is adjacent to the condensate collector to cool water vapor collected in the condensate collector.
 12. A method of controlling a refrigerator, comprising: heating water by a heater and supplying the heated water to a tray of an ice maker by a water supplier so as to generate water vapor by raising a temperature of water supplied into the tray above a boiling point; cooling the tray by a cooler so as to turn water, of which a dissolved air concentration is reduced due to the generation of the water vapor, in the tray into ice; and collecting water vapor from the tray by a condensate collector, separating the collected water vapor into condensate and air, and transferring the separated condensate to the water supplier.
 13. The method of claim 12, wherein the supplying the heated water to the tray includes lowering an internal pressure of the tray below an external pressure of the refrigerator.
 14. The method of claim 13, wherein the transferring the separated condensate to the water supplier includes transferring air separated from the collected water vapor to a pump configured to adjust an internal pressure of the tray.
 15. The method of claim 12, wherein the cooling the tray includes cooling the tray, based on an internal pressure of the tray exceeding a threshold after supplying water into the tray. 